1. Field of the Invention
The present invention generally relates to an image reading apparatus, image recording apparatus and image forming apparatus, and more particularly to an image forming apparatus such as facsimile machine having a photocopy function, and an image reading apparatus and image printing apparatus incorporated in the image forming apparatus.
2. Description of the Related Art
In recent years, prevailing are copy machines and facsimile machines having a photocopy function (fax-copy machines) that are equipped with a flat bed scanner (FBS) for scanning a stationary image on an original document placed on a platen and an automatic document feeder (ADF) for feeding plural sheets of original paper set in a document hopper sheet by sheet and scanning images on the original paper.
In this type of fax-copy machines, ADF has a paper feed motor for moving sheets loaded into the document hopper, and FBS has a drive motor for moving a carriage from a scanning start position to an end position.
These and other motors used in the fax-copy machine are mostly stepper motors since original document positioning and carriage positioning should be done at high accuracy. Conventionally each of the stepper motors has its own motor driver.
However, the motor driver is generally expensive so that the fax-copy machine that needs a plurality of motor drivers is also costly.
On the other hand, a motor driver that has two circuits adapted to drive two stepper motors is also known. If this motor driver is employed, a necessary cost per one stepper motor is reduced as compared with the motor driver that has only one circuit. However, the two-circuit motor driver is also expensive so that it does not contribute to manufacturing cost reduction very much.